Electric circuit having distributed constants



March 9, 1965 HISAO MAEDA 3,173,080

ELECTRIC CIRCUIT HAVING DISTRIBUTED CONSTANTS Filed May 24. 1960 eg 34/ ix t1 t1 F ?E$EE E SES SF an M Input Output Side Side N VE-IV 7 0R l-l/SAO MAf-DA QWX M United States Patent ELECTRIC CIRCUIT HAVING DISTRIBUTED CONSTANTS Hisao Maeda, 13 Shiba-koen, Minato-lru, Tokyo-t0, Japan Filed May 24, 1960, Ser. No. 31,332

Claims priority, application Japan, May 25, 1959,

34/ 16,745 2 Claims. (Cl. 323-76) This invention relates to a new and improved, distributed constant circuit.

It is an object of the invention to provide a distributed constant circuit of small physical dimensions.

It is another object of the invention to provide a distributed constant circuit as mentioned above wherein, through the use of a relatively simple construction, the magnetic flux of the input signal is effectively prevented from influencing the output portion of the coil.

It is yet another object of the invention to provide a distributed constant circuit as described above and having a construction which permits simple adjustments and changes, whereby various characteristics of the distributed constant circuit may be readily varied to suit its intended use.

The manner in which the foregoing as well as other objects and advantages may best be achieved will be understood more fully from a consideration of the following description of one representative embodiment of the invention, taken in conjunction with the accompanying drawing in which:

FIG. 1 is a perspective view showing the coil used in the embodiment of this invention;

FIG. 2 is a perspective view showing the ceramic bobbin of the coil with ground electrodes, of the embodiment of FIG. 1;

FIG. 3 is a perspective view showing a conventional ferrite core of integral bar form;

FIG. 4 is a perspective view showing ferrite plates in their approximate, relative positions as used in the embodiment of this invention;

FIG. 5 is a perspective view showing a ferrite tube;

FIG. 6 is an electrical connection diagram showing a circuit which is electrically equivalent to the embodiment of the invention.

Referring to the drawing, one of the members of the embodiment is a ceramic bobbin C of a material having a high dielectric constant, such as titanium oxide. A conductor line L in coil form is wound about said ceramic bobbin C, which is provided on its inner surface with ground electrodes E. The conventional ferrite core F of an electric coil, as shown in FIG. 3 has a diameter which enables it to be inserted in the said ceramic bobbin C. The unique ferrite core of the invention which is used in place of the core of FIG. 3 has a construction, as indicated in FIG. 4, wherein a plurality of ferrite plates F each of thickness t are assembled coaxially in alternate, laminate arrangement with spacers S, each of thickness t In practice, said spacers may be made of insulation material having low high-frequency loss. The thickness of the ferrite plates are approximately the same as, or are thinner than that of the spacers. The ferrite tube F shown in FIG. 5 has an inner diameter which will enable it to be fitted about the aforesaid coil on the said ceramic bobbin C.

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If, as a supposition, ground electrodes E are installed as shown in FIG. 2 in the ceramic bobbin C of FIG. 1 about which a coil has been wound, and the conventional ferrite core F of FIG. 3 is inserted into the said ceramic bobbin C, both the distributed inductance and distributed capacitance will increase, and a distributed constant circuit of small dimensions will be obtained. In this case, however, since the magnetic flux of the input signal passes through the magnetic ferrite core placed in the center along the coil axis and has effect up to the output portion of the coil, this detrimental effect must be prevented.

The said effect is effectively prevented by the present invention, wherein the afore-described, laminate ferrite core of FIG. 4 is inserted in the coil in place of the core F of FIG. 3. With the said laminate core, since the magnetic flux of the coil is divided into divisions corresponding to the number of ferrite plates F and is highly concentrated locally, and the magnetic flux due to the current of the input signal has very little effect at the output side. The equivalent electric circuit of the above arrangement is shown in FIG. 6.

When a ferrite tube as shown in FIG. 5 is fitted onto the outer surface of the coil, the concentration of the magnetic flux in each division is further improved. The term ground electrodes of this invention does not necessarily mean that these must be grounded as a matter of course. By using a conducting wire of ribbon form or a printed conductor for the coil wire, the distributed capacitance can be increased. Furthermore, by suitably covering the surface of the coil wire shown in FIG. 1, of this invention with a substance having a high dielectric constant, such as styrene liquid, it is possible to increase the distributed capacitance between adjacent turns of coil.

Still furthermore, by applying a coating of ferrite powder on the coil, it is possible also to increase the distributed inductance. In this invention, it is also possible to make the distributed capacitance variable by varying the area of the grounded electrodes. Furthermore, in this invention, it is also possible to wind the coil in bifilar winding of two windings, or a greater number of windings. Also in this invention, it is possible to grind the ceramic bobbin to have a uniform thickness or to have a tapered thickness so as to vary the distributed capacitance progressively.

It is also possible in this invention to use inductance or capacitances of lumped constants depending on the necessity.

Although this invention has been described, for the most part, with respect to a particular embodiment thereof, it is not to be so limited as changes and modifications may be made therein which are within the full intended scope of the invention, as defined by the appended claims.

What I claim is:

1. An electric circuit having distributed constants, which comprises, in combination, a hollow tube of a material having a high dielectric constant; a bare wire coil longitudinally wound thereon essentially spirally; evenly spaced ground electrode strips fixedly disposed parallel to each other on the inner surface of said hollow tube and traversing the entire length thereof; a plurality of parallel and like ferrite core plates of suitable thickness; spacers between said core plates of approximately the same thickness as said core plates; said core plates and said spacers being inserted in a coaxial, laminate arrangement within the interior of said hollow tube in the longitudinal direction thereof; and a ferrite tube fitting over the outer surface of said coil.

2. An electric circuit having distributed constants, which comprises, in combination, a hollow tube of a material having a high dielectric constant; a bare Wire coil longitudinally wound thereon essentially spirally; even-spaced ground electrode strips fixedly disposed parallel to each other on the inner surface of said hollow tube and traversing the entire length thereof; a plurality of parallel and like ferrite core plates of suitable thickness; spacers between said core plates of approximately the same thickness as said spacers; said core plates and said spacers being inserted in coaxial, laminate arrangcment within the interior of said hollow tube in the longitudinal direction thereof; and a coating of ferrite powder applied over said coil.

References Cited in the file of this patent UNITED STATES PATENTS 2,457,212 Di Toro Dec. 28, 1948 2,594,915 Guillernant Apr. 29, 1952 2,630,560 Earl et al. Mar. 3, 1953 FOREIGN PATENTS 609,708 Great Britain Oct. 6, 1948 649,398 Great Britain Ian. 24, 1951 985,136 France Apr. 22, 1949 914,635 Germany Aug. 23, 1954 

1. AN ELECTRIC CIRCUIT HAVING DISTRIBUTED CONSTANTS, WHICH COMPRISES, IN COMBINATION, A HOLLOW TUBE OF A MATERIAL HAVING A HIGH DIELECTRIC CONSTANT; A BARE WIRE COIL LONGITUDINALLY WOUND THEREON ESSENTIALLY SPIRALLY; EVENLY SPACED GROUND ELECTRODE STRIPS FIXEDLY DISPOSED PARALLEL TO EACH OTHER ON THE INNER SURFACE OF SAID HOLLOW TUBE AND TRAVERSING THE ENTIRE LENGTH THEREOF; A PLURALITY OF PARALLEL AND LIKE FERRITE CORE PLATES OF SUITABLE THICKNESS; SPACERS BETWEEN SAID CORE PLATES OF APPROXIMATELY THE SAME THICKNESS AS SAID CORE PLATES; SAID CORE PLATES AND SAID SPACERS BEING INSERTED IN A COAXIAL, LAMINATE ARRANGEMENT WITHIN THE INTERIOR OF SAID HOLLOW TUBE IN THE LONGITUDINAL DIRECTION THEREOF; AND A FERRITE TUBE FITTING OVER THE OUTER SURFACE OF SAID COIL. 